Technical Field
The invention relates a radio frequency (RF) receiver, and more particularly, relates to a RF receiver having a smart listening mode.
Description of Related Art
In a communication system, data are being exchanged between a transmitting end and a receiving end, where the data is carried by a RF signal. When quadrature modulation is utilized to transmit the data in a communication system, the transmitting end modulates signal carrying the data into an in-phase (I) and a quadrature-phase (Q) signal components that are offset by 90 degrees in phase. The two signal components are then superposed to generate a RF signal for transmission. At the receiving end, a receiver receives the RF signal via an antenna and performs demodulation to obtain information carried by the RF signal. For the demodulation, the receiver has to provide two separate signal channels (or paths), such as I channel and Q channel. In each channel, the RF signal may be filtered, amplified, processed in order to obtain signal characteristic and convert the RF signal into digital data.
Since the receiving end does not know the timing of the data transmission, the receiver would be activated, waiting for a data packet. This activation of the receiver would consume an amount of power. Furthermore, the antenna is exposed to various RF signals propagating in the open air, so the receiver would also process these RF signals. However, some of these RF signals are not directed to a device at the receiving end. The process performed for these RF signals would also consume power. Therefore, it is desirable to reduce the power consumption while waiting for a valid data packet to arrive.
Nothing herein should be construed as an admission of knowledge in the prior art of any portion of the present invention. Furthermore, citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention, or that any reference forms a part of the common general knowledge in the art.